The invention relates to a coolant jacket for a liquid-cooled cylinder head for an internal combustion engine with a crankcase, wherein the cylinder head has a gas exchange intake side with two gas exchange intake valves and a gas exchange outlet side with two gas exchange outlet valves.
A coolant jacket for a cylinder head that is cooled with liquid is known from prior art document DE 102 51 360 B4, on which the present invention is based. DE 102 51 360 B4 describes a liquid-cooled cylinder head that is configured for an internal combustion engine that has multiple cylinders. The cylinder head has a coolant flow that flows from a coolant intake on an outlet side to a coolant outlet on an intake side. Furthermore, the cylinder head has a coolant chamber, which is defined by outer walls, a cylinder head bottom and a water chamber roof. The cylinder head has a rib, which hangs from the water chamber roof and, in so doing, projects, as a flow guiding element, more or less transversely to the coolant flow. Furthermore, at least one intake valve and two outlet valves with gas exchange channels are arranged in each cylinder section. Furthermore, a coolant intake is provided from the bottom in a coolant distributor channel. Starting from this coolant distributor channel, a side coolant channel passes between the gas exchange channel of an outlet valve and a screw hole of a cylinder head screw. A central coolant channel passes between the two gas exchange channels of the outlet valves. The liquid-cooled cylinder head that is described in DE 102 51 360 B4 is characterized in that the central coolant channel guides the coolant flow to the rib in the water chamber root and this rib is connected to the spark plug hole on the water chamber roof and has a flow-guiding manifold in a region of an impingement point of the coolant flow from the central coolant channel.
This type of coolant jacket, known from the prior art, does not optimally cool the cylinder head, in particular, in the region of the highest volume of heat input between the gas exchange outlet valves and the ignition device.
The object of the present invention is to provide a coolant jacket that is configured for a liquid-cooled cylinder head and that does not exhibit the aforementioned drawback.
This and other objects are achieved by providing a coolant jacket for a liquid-cooled cylinder head for an internal combustion engine with a crankcase, wherein the cylinder head has a gas exchange intake side with two gas exchange intake valves and a gas exchange outlet side with two gas exchange outlet valves. A fuel injection valve is provided on the intake side and an ignition device is provided on the outlet side between the gas exchange valves. The coolant jacket extends as a first partial coolant jacket on the outlet side, coming from the crankcase, between the gas exchange outlet valves, and then radially outside around the ignition device and the fuel injection valve and further in the direction of the intake side and the crankcase.
According to the invention, the coolant jacket is designed in such a way that the coolant flows from the outlet side from the crankcase, coming centrally relative to the cylinder into the cylinder head (optionally, also laterally next to the gas exchange outlet channels) and there in close proximity to the combustion chamber roof between the gas exchange outlet valves and around the ignition device and the fuel injection device in the direction of the intake side. In particular, the coolant jacket envelops to a large extent the threaded region of the ignition device.
In an advantageous embodiment, the cylinder head includes a gas exchange outlet channel on the gas exchange outlet side, wherein a second and a third partial coolant jacket are provided. The second and third partial cooling jackets, arranged on both sides adjacent to the first partial coolant jacket, extend, coming from the crankcase, to a large extent around the gas exchange outlet channel and merge with the first partial coolant jacket in the direction of the gas exchange intake side. In a further advantageous embodiment, the second and third partial coolant jackets extend, coming from the gas exchange outlet channel, on both the sides of the gas exchange valves, in the direction of the gas exchange intake side and on the intake side again in the direction of the crankcase. These embodiments improve once more the entire cooling of the cylinder head according to the invention, because the heat removal from the hot areas is homogenized.
According to a further preferred embodiment, an exhaust gas manifold is provided for the cylinder head on the gas exchange outlet side, wherein the second and third partial coolant jackets extend at least in sections into the exhaust gas manifold. With this embodiment, an exhaust gas manifold can also be temperature controlled in an advantageous way. This exhaust gas manifold can be either mounted on the cylinder head as a separate component or is integral with the cylinder head.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.